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Date:   Mon, 15 Nov 2021 11:02:26 +0100
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Subject: Re: [PATCH] xen/privcmd: make option visible in Kconfig
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To:     =?UTF-8?Q?Thomas_Wei=c3=9fschuh?= <linux@weissschuh.net>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        xen-devel@lists.xenproject.org
CC:     linux-kernel@vger.kernel.org
References: <20211113083821.71060-1-linux@weissschuh.net>
From:   Jan Beulich <jbeulich@suse.com>
In-Reply-To: <20211113083821.71060-1-linux@weissschuh.net>
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On 13.11.2021 09:38, Thomas Wei=C3=9Fschuh wrote:
> This configuration option provides a misc device as an API to userspace.
> Make this API usable without having to select the module as a transitive
> dependency.
>=20
> This also fixes an issue where localyesconfig would select
> CONFIG_XEN_PRIVCMD=3Dm because it was not visible and defaulted to
> building as module.
>=20
> Signed-off-by: Thomas Wei=C3=9Fschuh <linux@weissschuh.net>
>=20
> ---
>=20
> Note: If CONFIG_XEN_PRIVCMD really is only meant to be selected by
> XENFS, then the issue can be fixed by removing its "default m"
> definition.
> ---
>  drivers/xen/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index a1b11c62da9e..c14d8631b8f6 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -259,7 +259,7 @@ config XEN_SCSI_BACKEND
>  	  if guests need generic access to SCSI devices.
> =20
>  config XEN_PRIVCMD
> -	tristate
> +	tristate "Xen privileged domain-0 commands"
>  	depends on XEN
>  	default m

While I agree with adding a prompt here, I'm not sure why you've added
"domain-0" to its wording. Aiui this interface is equally available in
DomU-s, just that they would be able to only (successfully) use a more
restricted set of hypercalls. Otherwise the XEN dependency would need
to be changed to XEN_DOM0 at the same time as adding a prompt, or the
prompt's visibility be restricted to XEN_DOM0.

Jan